Partial Thickness Rotator Cuff Tears: Treatment

Partial thickness rotator cuff tears can result from intrinsic cuff degeneration and tendinopathy absent an injury or impingement. The lack of uniformity of collagen bundles and the paucity of vascular supply contributes to weakness, especially along the articular aspect of the rotator cuff. These degenerative tears often exit the articular surface and can be well visualized at surgery, but sometimes can be entirely contained within the cuff (intrasubstance), and therefore easily missed.

As noted earlier, extrinsic impingement due to narrowing of the supraspinatus outlet can result in chronic cuff abrasion leading to a partial cuff tear. Histological changes consistent with trauma have been found on the undersurface of cadaveric acromion specimens with bursal surface tears but not in those with articular surface tears. This suggests that bursal-surface tears may be more likely to be related to abrasion of the cuff by the acromion.

Furthermore, extrinsic impingement due to coracoacromial arch narrowing has been postulated to cause partial tears on the articular side as well as the bursal surface of the cuff based on transmural shear stress leading to fiber failure of the laminated cuff.

Trauma, absent impingement, can cause a partial thickness tear, usually leading to a partial avulsion of the articular surface of the cuff. This can be the result of repetitive microtrauma or simply a single high-energy episode. This type of avulsion injury has been named the “PASTA” lesion (partial articular sided tendon avulsion) (128).

The symptoms of partial thickness rotator cuff tears are nonspecific and may overlap with impingement, rotator cuff tendonitis, and small, full thickness rotator cuff tears. Similar to the impingement population, most patients have a painful arc of motion between 60 and 120 degrees of elevation. They may also have loss of motion with posterior capsular tightness and resultant restriction of internal rotation.

The impingement signs described by Neer (pain with forced passive forward elevation) and Hawkins (pain with passive internal rotation of the arm placed in 90 degrees of forward flexion) are positive in nearly all patients with symptomatic partial thickness rotator cuff tears. Strength is usually preserved on clinical examination; however, pain inhibition may result in an apparent loss of strength and in a decrease in active range of motion in these patients with a partially torn rotator cuff.

The clinical course of patients with partial thickness rotator cuff tears is often indistinguishable from that of patients with impingement syndrome, tendonitis, or small, full thickness rotator cuff tears. Symptoms may also be difficult to differentiate from bicipital tendonitis, labral or SLAP lesions, and mild cases of adhesive capsulitis.

There is currently no universally accepted classification system for partial thickness rotator cuff tears. Evaluating the results of treatment has been challenging due to this lack of conformity. Although the classification of partial tears continues to be refined, the system most commonly used is that proposed by Ellman in which the depth of the tear is estimated:

Grade I: 1-3 mm,

Grade II: 3-6mm, and

Grade III: 6mm or greater .

Anatomic knowledge of the “footprint” makes this assessment more uniform and reproducible. If the average supraspinatus “footprint” is approximately 12 mm in size, it is possible to grade the percentage of tearing. Using the “footprint” as a guide, if more than 6 mm of the footprint is exposed, a greater than 50% tear of the supraspinatus insertion has occurred. Snyder has proposed a grading system in which the articular and bursal sides of the cuff are evaluated separately in an effort to be more precise in judging severity.

Individuals with a suspected partial tear due to extrinsic impingement or intrinsic tendinopathy are treated in a similar fashion as those with impingement syndrome. Subacromial bursal inflammation is controlled with activity modification, nonsteroidal anti-inflammatory medication, and the judicious use of injectable corticosteroids.

The role of rehabilitation to restore normal joint mechanics and strengthen the rotator cuff and parascapular musculature has been proposed to reduce the progression of rotator cuff disease in those with both external and internal impingement.

The role of the external rotators which act as humeral head depressors may play a role in reducing external impingement thus reducing further mechanical impingement of the cuff from the coracoacromial arch.

Partial thickness tears that fail to respond to conservative measures usually require surgical intervention, including debridement alone, debridement in conjunction with a subacromial decompression, and decompression combined with a rotator cuff repair, either mini-open or arthroscopic.

Arthroscopic debridement alone of partial tears has led to mixed results . One study evaluating the results for decompression alone recorded failure rates exceeding 50% . Furthermore treating a partial tear without addressing potential underlying causes such as instability has also been associated with a high failure rate.

Arthroscopic subacromial decompression combined with arthroscopic debridement of partial tears has also led to mixed results. Several investigators have described failure rates ranging from 20 to 30% in this treatment group . Ryu reported on 35 patients treated with an arthroscopic subacromial decompression and debridement with a follow-up of 23 months and had 86% good results with bursal sided tears exhibiting a more favorable result as compared to articular-sided lesions

Because of concerns about cuff integrity and tear progression, repair of extensive partial rotator cuff tears has been recommended. Ellman was one of the first to recommend arthroscopic subacromial decompression along with open repair of significant, partial tears of the rotator cuff. Fukuda, reporting on 66 patients with partial tears treated with an open acromioplasty and repair, achieved satisfactory results in 94% of his patients.

Weber has documented the clear advantage of repairing separate partial thickness tears in conjunction with subacromial decompression. His re-operation rate was significantly lower for those treated with a concomitant repair versus those who simply underwent a debridement. In another study, Weber determined that by completing the articular-sided tear, excising unhealthy tissue and advancing healthy tendon back to its attachment site, an all-arthroscopic approach led to results equal to those reported with the mini-open technique.

Bursal-sided partial tears of the rotator cuff are usually a direct result of mechanical impingement occurring at the arch. These injuries are readily visualized at surgery and the depth of the tear can be accurately estimated in most cases. For those with a Grade I or II partial tear in conjunction with impingement, a simple debridement in association with a subacromial decompression may be the most appropriate treatment.

For those individuals who have a significant partial tear, Grade III, and higher post-operative expectations of their shoulder, a more aggressive approach including repair of the partial tear in addition to the decompression may be more suitable.

The articular-sided tears occur two to three times more commonly than bursal-sided tears, and may not necessarily be associated with the impingement phenomenon. Repetitive traction forces or underlying primary pathology such as a superior labral injury or symptomatic capsular redundancy can result in articular-sided cuff tears. Additionally in some instances, internal impingement may be the source of the tearing.

The GIRD syndrome (glenohumeral internal rotation deficit) has been established as a common pathway for articular-sided partial rotator cuff injuries. Loss of internal rotation leads to abnormal joint mechanics with subsequent loss of the normal cam effect on the glenohumeral joint. This permits pathologic hyper-external rotation, superior labral pathology and cuff tearing on a tensile failure basis. Others have postulated a direct contact lesion occurring between the articular surface of the cuff and the posterior-superior glenoid and labrum.

Grade I and II articular-sided partial thickness tears should be debrided. Careful consideration to an underlying primary pathology, especially instability, must be given, and if discovered, treated concomitantly. A Grade III articular-sided partial tear deserves a repair, either trans-tendon or by completing the tear and converting to a full thickness lesion. Whether a decompression is warranted or not should be determined by

the presence or absence of subacromial changes. Those lacking pathologic changes in the subacromial space such as coacoacromial ligament fraying should not be treated with a decompression as further instability is potentially incurred.

If a repair of a partial tear is performed, the arthroscopic trans-tendon technique for treating significant partial articular sided rotator cuff tears (‘PASTA’ lesion: partial articular-sided tendon avulsion) has been described.
This method seeks to replace the partially torn tendon to its native “footprint” on the tuberosity, preserving the remaining fiber attachment. It is an alternative technique to the arthroscopic approach championed by Weber in which the tear is first converted to a full-thickness injury and then repaired arthroscopically.